Patent GB-1040664-A (GB)
Title: Film scanning
IPC: H04N3/36
Filed: 1964-03-26
Abstract: 1,040,664. Cine films. COLUMBIA BROADCASTING SYSTEM, Inc. March 26, 1964 [March 29, 1963], No. 12880/64. Heading G2E. [Also in Division H4] In an arrangement for scanning a continuously moving cinematographic film 10, Fig. 1, to produce corresponding television signals by projecting an interlaced scanning raster from a cathode ray tube 22 through the film and on to a photo-multiplier 26, the scanning area 18 has a dimension in the direction of film conveyance equal to twice the pitch distance between the successive film frames and the scanning rate is synchronized with the speed of film conveyance by means of synchronizing signals derived from scanning, separately from the film frames, distinctive synchronizing information recorded on the film. Light source 27 directs light through the film 10 at an angle to the lens system 24 and 25 to a photo-cell 29 connected to a synchronizing signal detector circuit 30 which responds to the synchronizing marks 32, Fig. 3D, recorded between film frames which are different from any information recorded within the frames to initiate retrace of the vertical scanning motion. In the embodiment described, in which the cathode ray tube scans 60 fields/sec, the film 10 scanned is a print produced from a standard 24 frames/sec type film, the print containing the same information as the standard film but having every other frame duplicated in adjacent frames and the rest of the frames repeated three times in adjacent frames, Fig. 3C, so that the time relationship of the information contained in 24 frames of the original standard film is retained in 60 frames of the print. The film traverses the scanning area which has a height equal to twice that of the frame pitch P, Fig. 2A, at a rate such that a frame traverses a distance equal to the frame pitch P during each scansion S 1 , S 2 , and S 3 , the bottom edges of the picture forming the leading edges of the frames. The active vertical scansion begins at the top of frame A<SP>1</SP> and moves vertically, while oscillating horizontally, to the bottom of frame A<SP>1</SP> during 1/60 second at which time the top of frame B<SP>1</SP> occupies the point previously occupied by the top of frame A<SP>1</SP> and the return scansion initiated by detection of the synchonizing marks between frames, moves the spot to the top of frame B<SP>1</SP> during blanking Fig. 2B. During the movement of frame B<SP>1</SP> a full pitch distance P the second scansion S 2 , interlaced between the lines of scansion S 1 , takes place. Besides being intercalated the frames of the print may be anamorphosed or compressed in the direction of film movement, i.e. the vertical dimension of each frame may be reduced, so that the linear rate of film movement is the same as for the 30 frames per second used at the present time with film of the type described with reference to Fig.3B (not shown). The synchronizing marks may comprise a plurality of transverse lines 32, Fig. 3D, photographically recorded between adjacent frames and extending the full width of the frames into margin 35 on one side, the other margin being occupied by a sound track 36. Alternatively the synchronizing marks may only extend partially across the film width or they may be only recorded in the margin 35 and then they may be positioned at any location having a predetermined relation of the frame line. The synchronizing marks may comprise magnetic record segments between the frames or in the margin 35, in which case a magnetic detecting head is substituted for the photo-cell 29.